Fucoidan, a fucose containing sulfated carbohydrate polymer, inhibits a wide range of physiological processes which involve cell-cell interactions such as sperm-egg fertilization, tumor growth and the binding of lymphocytes to the endothelial cells. Some of these effects are exhibited by sulfated fucose. To evaluate the role of monomeric fucose sulfates, suitably blocked derivatives of methyl-L-fucoside have been prepared. From these, mono- and disulfated derivatives of known structure will be synthesized.